Limits of coherent supercontinuum generation in normal dispersion fibers
Limits of coherent supercontinuum generation in normal dispersion fibers
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DOI：
10.1364/josab.34.000764
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发表时间：
2017-04-01
影响因子：
1.9
通讯作者：
Feurer, Thomas
中科院分区：
文献类型：
--
作者：
Heidt, Alexander M.;Feehan, James S.;Feurer, Thomas
我们研究了在全正常色散（ANDi）光纤中的相干和噪声种子非相干连续谱产生之间的大量未探索的过渡，并表明可以用长达1.5 ps的持续时间的长泵浦脉冲产生具有一个倍频程的光谱带宽的高度相干超连续谱，对应于高达N = 600的孤子阶数。就N而言，这对应于与异常色散泵浦相比相干状态的大约50倍增加。在相干和非相干光谱展宽之间的过渡区，我们观察到非线性现象的表现，我们称之为非相干云形成和非相干光波破碎，它们分别导致超连续谱（SC）分量的逐渐或瞬时相干崩溃。受激拉曼散射和参量四波混频在ANDi光纤中SC产生过程中所起的作用比以前认识到的更广泛：它们的非线性耦合有助于在短泵浦脉冲持续时间抑制非相干动力学，而它是负责在长脉冲制度中观察到的噪声的非相位匹配参量放大。我们进一步讨论了光纤设计的SC相干性的依赖，并提出了基本的实验验证我们的研究结果使用单次检测的SC光谱产生的皮秒脉冲。这项工作概述了宽带相干光源发展的进一步潜力和局限性，如计量，非线性成像和超快光子学等应用。(C)2017美国光学学会
We study the largely unexplored transition between coherent and noise-seeded incoherent continuum generation in all-normal dispersion (ANDi) fibers and show that highly coherent supercontinua with spectral bandwidths of one octave can be generated with long pump pulses of up to 1.5 ps duration, corresponding to soliton orders of up to N = 600. In terms of N, this corresponds to an approximately 50 times increase of the coherent regime compared to anomalous dispersion pumping. In the transition region between coherent and incoherent spectral broadening, we observe the manifestation of nonlinear phenomena that we term incoherent cloud formation and incoherent optical wave breaking, which lead to a gradual or instantaneous coherence collapse of supercontimuum (SC) spectral components, respectively. The role played by stimulated Raman scattering and parametric four-wave mixing during SC generation in ANDi fibers is shown to be more extensive than previously recognized: their nonlinear coupling contributes to the suppression of incoherent dynamics at short pump pulse durations, while it is responsible for non-phase-matched parametric amplification of noise observed in the long pulse regime. We further discuss the dependence of SC coherence on fiber design, and present basic experimental verifications for our findings using single-shot detection of SC spectra generated by picosecond pulses. This work outlines both the further potential as well as the limitations of broadband coherent light source development for applications such as metrology, nonlinear imaging, and ultrafast photonics, among others. (C) 2017 Optical Society of America